Vulnerability Description
Plack-Middleware-Session before version 0.35 for Perl generates session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. Predicable session ids could allow an attacker to gain access to systems.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/plack/Plack-Middleware-Session/commit/1fbfbb355e34e7f4b3906f6
- https://github.com/plack/Plack-Middleware-Session/pull/52
- https://metacpan.org/release/MIYAGAWA/Plack-Middleware-Session-0.34/source/lib/P
- https://security.metacpan.org/docs/guides/random-data-for-security.html
- http://www.openwall.com/lists/oss-security/2025/07/16/4
FAQ
What is CVE-2025-40923?
CVE-2025-40923 is a vulnerability with a CVSS score of 7.3 (HIGH). Plack-Middleware-Session before version 0.35 for Perl generates session ids insecurely. The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, a...
How severe is CVE-2025-40923?
CVE-2025-40923 has been rated HIGH with a CVSS base score of 7.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-40923?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.